Migrants disembark from a Coast Guard boat as they arrive in the Sicilian harbour of Palermo(Reuters)

Another boat carrying refugees has reportedly sank in the Mediterranean leaving more than 40 people drowned.

Four survivors of the shipwreck told Italian police in Trapani, Sicily, their rubber vessel carrying 45 people sank off the Libyan coast, the International Organization for Migrants (IOM) told IBTimes UK.

They were among 580 migrants brought to the port on Thursday. The agency said the migrants were found floating in the sea by a helicopter and were rescued by the Italian Naval ship Foscari.

The report comes after as many as 400 migrants fleeing Libya are feared to have drowned when their boat capsized 24 hours after departing the North African coast. Italy's coastguard has rescued 144 people but several hundred others are feared dead given the size of the vessel.

Italian coastguards have rescued 893 migrants from boats in distress off the Libyan coast and are bringing them to two Sicilian coastal towns that are already struggling with the influx of refugees from Libya.

The Italian coastguard said they have rescued up to 10,000 people since 10 April.